The Pentagon says it does not know how often the children of service members sexually assault one another on military bases.

To answer that question, The Associated Press filed dozens of Freedom of Information Act requests with the main law enforcement agencies for the Army, Navy, Air Force and Marines, as well as with the Pentagon school system that educates elementary and secondary students on installations worldwide.

AP sought information on sex assaults reported on base from the start of 2007 through the summer of 2017, in which both the civilian victim and offender were under 18.

Not all records were available. The Pentagon”s school system, for example, said it destroys records after five years. When documents were provided, agencies excluded details they said might identify juveniles.

 The Naval Criminal Investigative Service, which handles all felony-level sex offenses for the Navy and Marine Corps, provided information on 100 cases.

 The Army Criminal Investigation Command released a spreadsheet with 223 cases. Reporters later learned the information included only cases the command defined as “closed,” instead of all reported assaults. The command”s definition  uncommon for law enforcement  required cases to exhaust a lengthy process, culminating in agents shipping files to an Army records repository. The command also failed to provide information on other reported assaults in a case-management database the AP learned about.

 The Air Force secretary”s office provided a list of 20 sexual assaults, but that included only those reports kept in a data system maintained by the branch”s front-line police unit. AP also requested investigative files from major bases and the Air Force Office of Special Investigations provided limited information on two other cases, bringing the total to 22.

 The Department of Defense Education Activity, which runs Pentagon schools, provided information on 67 cases starting only with the 2011-2012 school year based on its “serious incident” reporting system. Some 21 assaults appeared to be also represented in military law enforcement data and were excluded from the total count.

AP identified an additional 205 cases, mostly from a database in which school administrators can log student misconduct. Reporters discovered the existence of the database after the school system had provided its official count. Eventually, the school system released logs showing 157 confirmed cases of sexual misconduct, mostly fondling and groping that fit the criteria for a federal felony sex assault charge. AP did not count some cases described as “inappropriate touching” or “sexual harassment” because of a lack of details. Administrators noted that school officials weren”t required to use the database, and last year one third did not.

AP found 48 other cases, most of them criminally investigated, through interviews and a sampling of state and local authorities, who on some bases have policing or prosecutorial power.

In total, AP identified 596 cases of sexual assault among children and teens on U.S. military bases. That total is a certain undercount.

The Office of the Secretary of Defense could not say how many children and teens live on bases, but the Pentagon”s school system has about 71,000 students.